Operating method related to selection of relay ue in wireless communication system

ABSTRACT

An embodiment relates to a method for selecting a sidelink relay in a wireless communication system. The method comprises: selecting, by remote UE, at least one candidate relay UE; and selecting, by the remote UE, relay UE from among the at least one candidate relay UE, wherein the selection of the at least one candidate relay UE is on the basis of sidelink signal strength of each of the at least one candidate relay UE, and the selection of the relay UE is on the basis of comparison between a cell ID of each of the at least one candidate relay UE and a cell ID selected according to Uu link signal strength.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore particularly, to a method and apparatus for selecting a relay UE bya remote UE.

BACKGROUND ART

A wireless communication system uses various radio access technologies(RATs) such as long term evolution (LTE), LTE-advanced (LTE-A), andwireless fidelity (WiFi). 5th generation (5G) is such a wirelesscommunication system. Three key requirement areas of 5G include (1)enhanced mobile broadband (eMBB), (2) massive machine type communication(mMTC), and (3) ultra-reliable and low latency communications (URLLC).Some use cases may require multiple dimensions for optimization, whileothers may focus only on one key performance indicator (KPI). 5Gsupports such diverse use cases in a flexible and reliable way.

eMBB goes far beyond basic mobile Internet access and covers richinteractive work, media and entertainment applications in the cloud oraugmented reality (AR). Data is one of the key drivers for 5G and in the5G era, we may for the first time see no dedicated voice service. In 5G,voice is expected to be handled as an application program, simply usingdata connectivity provided by a communication system. The main driversfor an increased traffic volume are the increase in the size of contentand the number of applications requiring high data rates. Streamingservices (audio and video), interactive video, and mobile Internetconnectivity will continue to be used more broadly as more devicesconnect to the Internet. Many of these applications require always-onconnectivity to push real time information and notifications to users.Cloud storage and applications are rapidly increasing for mobilecommunication platforms. This is applicable for both work andentertainment. Cloud storage is one particular use case driving thegrowth of uplink data rates. 5G will also be used for remote work in thecloud which, when done with tactile interfaces, requires much lowerend-to-end latencies in order to maintain a good user experience.Entertainment, for example, cloud gaming and video streaming, is anotherkey driver for the increasing need for mobile broadband capacity.Entertainment will be very essential on smart phones and tabletseverywhere, including high mobility environments such as trains, carsand airplanes. Another use case is augmented reality (AR) forentertainment and information search, which requires very low latenciesand significant instant data volumes.

One of the most expected 5G use cases is the functionality of activelyconnecting embedded sensors in every field, that is, mMTC. It isexpected that there will be 20.4 billion potential Internet of things(IoT) devices by 2020. In industrial IoT, 5G is one of areas that playkey roles in enabling smart city, asset tracking, smart utility,agriculture, and security infrastructure.

URLLC includes services which will transform industries withultra-reliable/available, low latency links such as remote control ofcritical infrastructure and self-driving vehicles. The level ofreliability and latency are vital to smart-grid control, industrialautomation, robotics, drone control and coordination, and so on.

Now, multiple use cases will be described in detail.

5G may complement fiber-to-the home (FTTH) and cable-based broadband (ordata-over-cable service interface specifications (DOCSIS)) as a means ofproviding streams at data rates of hundreds of megabits per second togiga bits per second. Such a high speed is required for TV broadcasts ator above a resolution of 4K (6K, 8K, and higher) as well as virtualreality (VR) and AR. VR and AR applications mostly include immersivesport games. A special network configuration may be required for aspecific application program. For VR games, for example, game companiesmay have to integrate a core server with an edge network server of anetwork operator in order to minimize latency.

The automotive sector is expected to be a very important new driver for5G, with many use cases for mobile communications for vehicles. Forexample, entertainment for passengers requires simultaneous highcapacity and high mobility mobile broadband, because future users willexpect to continue their good quality connection independent of theirlocation and speed. Other use cases for the automotive sector are ARdashboards. These display overlay information on top of what a driver isseeing through the front window, identifying objects in the dark andtelling the driver about the distances and movements of the objects. Inthe future, wireless modules will enable communication between vehiclesthemselves, information exchange between vehicles and supportinginfrastructure and between vehicles and other connected devices (e.g.,those carried by pedestrians). Safety systems may guide drivers onalternative courses of action to allow them to drive more safely andlower the risks of accidents. The next stage will be remote-controlledor self-driving vehicles. These require very reliable, very fastcommunication between different self-driving vehicles and betweenvehicles and infrastructure. In the future, self-driving vehicles willexecute all driving activities, while drivers are focusing on trafficabnormality elusive to the vehicles themselves. The technicalrequirements for self-driving vehicles call for ultra-low latencies andultra-high reliability, increasing traffic safety to levels humanscannot achieve.

Smart cities and smart homes, often referred to as smart society, willbe embedded with dense wireless sensor networks. Distributed networks ofintelligent sensors will identify conditions for cost- andenergy-efficient maintenance of the city or home. A similar setup can bedone for each home, where temperature sensors, window and heatingcontrollers, burglar alarms, and home appliances are all connectedwirelessly. Many of these sensors are typically characterized by lowdata rate, low power, and low cost, but for example, real time highdefinition (HD) video may be required in some types of devices forsurveillance.

The consumption and distribution of energy, including heat or gas, isbecoming highly decentralized, creating the need for automated controlof a very distributed sensor network. A smart grid interconnects suchsensors, using digital information and communications technology togather and act on information. This information may include informationabout the behaviors of suppliers and consumers, allowing the smart gridto improve the efficiency, reliability, economics and sustainability ofthe production and distribution of fuels such as electricity in anautomated fashion. A smart grid may be seen as another sensor networkwith low delays.

The health sector has many applications that may benefit from mobilecommunications. Communications systems enable telemedicine, whichprovides clinical health care at a distance. It helps eliminate distancebarriers and may improve access to medical services that would often notbe consistently available in distant rural communities. It is also usedto save lives in critical care and emergency situations. Wireless sensornetworks based on mobile communication may provide remote monitoring andsensors for parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly importantfor industrial applications. Wires are expensive to install andmaintain, and the possibility of replacing cables with reconfigurablewireless links is a tempting opportunity for many industries. However,achieving this requires that the wireless connection works with asimilar delay, reliability and capacity as cables and that itsmanagement is simplified. Low delays and very low error probabilitiesare new requirements that need to be addressed with 5G

Finally, logistics and freight tracking are important use cases formobile communications that enable the tracking of inventory and packageswherever they are by using location-based information systems. Thelogistics and freight tracking use cases typically require lower datarates but need wide coverage and reliable location information.

A wireless communication system is a multiple access system thatsupports communication of multiple users by sharing available systemresources (a bandwidth, transmission power, etc.). Examples of multipleaccess systems include a CDMA system, an FDMA system, a TDMA system, anOFDMA system, an SC-FDMA system, and an MC-FDMA system.

Sidelink (SL) refers to a communication scheme in which a direct link isestablished between user equipments (UEs) and the UEs directly exchangevoice or data without intervention of a base station (BS). SL isconsidered as a solution of relieving the BS of the constraint ofrapidly growing data traffic.

Vehicle-to-everything (V2X) is a communication technology in which avehicle exchanges information with another vehicle, a pedestrian, andinfrastructure by wired/wireless communication. V2X may be categorizedinto four types: vehicle-to-vehicle (V2V), vehicle-to-infrastructure(V21), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). V2Xcommunication may be provided via a PC5 interface and/or a Uu interface.

As more and more communication devices demand larger communicationcapacities, there is a need for enhanced mobile broadband communicationrelative to existing RATs. Accordingly, a communication system is underdiscussion, for which services or UEs sensitive to reliability andlatency are considered. The next-generation RAT in which eMBB, MTC, andURLLC are considered is referred to as new RAT or NR. In NR, V2Xcommunication may also be supported.

FIG. 1 is a diagram illustrating V2X communication based on pre-NR RATand V2X communication based on NR in comparison.

For V2X communication, a technique of providing safety service based onV2X messages such as basic safety message (BSM), cooperative awarenessmessage (CAM), and decentralized environmental notification message(DENM) was mainly discussed in the pre-NR RAT. The V2X message mayinclude location information, dynamic information, and attributeinformation. For example, a UE may transmit a CAM of a periodic messagetype and/or a DENM of an event-triggered type to another UE.

For example, the CAM may include basic vehicle information includingdynamic state information such as a direction and a speed, vehiclestatic data such as dimensions, an external lighting state, pathdetails, and so on. For example, the UE may broadcast the CAM which mayhave a latency less than 100 ms. For example, when an unexpectedincident occurs, such as breakage or an accident of a vehicle, the UEmay generate the DENM and transmit the DENM to another UE. For example,all vehicles within the transmission range of the UE may receive the CAMand/or the DENM. In this case, the DENM may have priority over the CAM.

In relation to V2X communication, various V2X scenarios are presented inNR. For example, the V2X scenarios include vehicle platooning, advanceddriving, extended sensors, and remote driving.

For example, vehicles may be dynamically grouped and travel togetherbased on vehicle platooning. For example, to perform platoon operationsbased on vehicle platooning, the vehicles of the group may receiveperiodic data from a leading vehicle. For example, the vehicles of thegroup may widen or narrow their gaps based on the periodic data.

For example, a vehicle may be semi-automated or full-automated based onadvanced driving. For example, each vehicle may adjust a trajectory ormaneuvering based on data obtained from a nearby vehicle and/or a nearbylogical entity. For example, each vehicle may also share a dividingintention with nearby vehicles.

Based on extended sensors, for example, raw or processed data obtainedthrough local sensor or live video data may be exchanged betweenvehicles, logical entities, terminals of pedestrians and/or V2Xapplication servers. Accordingly, a vehicle may perceive an advancedenvironment relative to an environment perceivable by its sensor.

Based on remote driving, for example, a remote driver or a V2Xapplication may operate or control a remote vehicle on behalf of aperson incapable of driving or in a dangerous environment. For example,when a path may be predicted as in public transportation, cloudcomputing-based driving may be used in operating or controlling theremote vehicle. For example, access to a cloud-based back-end serviceplatform may also be used for remote driving.

A scheme of specifying service requirements for various V2X scenariosincluding vehicle platooning, advanced driving, extended sensors, andremote driving is under discussion in NR-based V2X communication.

DETAILED DESCRIPTION Technical Task

Technical task of embodiment(s) is to provide a relay UE selectingmethod, information included in a discovery message, etc.

Technical Solutions

In one technical aspect of the present disclosure, provided is a methodof selecting a sidelink relay in a wireless communication system, themethod including selecting at least one candidate relay UE by a remoteUE and selecting a relay UE from the at least one candidate relay UE bythe remote UE, wherein the selection of the at least one candidate relayUE may be based on a sidelink signal strength of each of the at leastone candidate relay UE and wherein the selection of the relay UE may bebased on comparison between a cell ID of each of the at least onecandidate relay UE and a cell ID selected according to a Uu link signalstrength.

In another technical aspect of the present disclosure, provided is aUser Equipment (UE) in a wireless communication system, the UE includingat least one processor and at least one computer memory operablyconnected to the at least one processor and storing instructions forenabling the at least one processor to perform operations when executed,the operations including selecting at least one candidate relay UE by aremote UE; and selecting a relay UE from the at least one candidaterelay UE by the remote UE, wherein the selection of the at least onecandidate relay UE may be based on a sidelink signal strength of each ofthe at least one candidate relay UE and wherein the selection of therelay UE may be based on comparison between a cell ID of each of the atleast one candidate relay UE and a cell ID selected according to a Uulink signal strength.

In another technical aspect of the present disclosure, provided is aprocessor performing operations for a User Equipment (UE) in a wirelesscommunication system, the operations including selecting at least onecandidate relay UE by a remote UE and selecting a relay UE from the atleast one candidate relay UE by the remote UE, wherein the selection ofthe at least one candidate relay UE may be based on a sidelink signalstrength of each of the at least one candidate relay UE and wherein theselection of the relay UE may be based on comparison between a cell IDof each of the at least one candidate relay UE and a cell ID selectedaccording to a Uu link signal strength.

In further technical aspect of the present disclosure, provided is anon-volatile computer-readable storage medium storing at least onecomputer program enabling at least one processor to perform operationsfor a relay UE when executed by the at least one processor, theoperations including selecting at least one candidate relay UE by aremote UE and selecting a relay UE from the at least one candidate relayUE by the remote UE, wherein the selection of the at least one candidaterelay UE may be based on a sidelink signal strength of each of the atleast one candidate relay UE and wherein the selection of the relay UEmay be based on comparison between a cell ID of each of the at least onecandidate relay UE and a cell ID selected according to a Uu link signalstrength.

The relay UE may have the same cell ID as the cell ID selected accordingto the Uu link signal strength.

Based on a plurality of candidate relay UEs having the same cell ID asthe cell ID selected according to the Uu link signal strength, theremote UE may consider the sidelink signal strength more preferentially.

The cell ID may be included in a discovery message.

The cell ID selected according to the Uu link signal strength may be anID of a cell of which signal strength among Uu link signals measured bythe relay is equal to or greater than a first threshold.

The cell ID selected according to the Uu link signal strength may be anID of a cell of which Uu link signal strength measured by the relaybelongs to a first range.

The at least one candidate relay UE may have the sidelink signalstrength equal to or greater than a second threshold.

The at least one candidate relay UE may have the sidelink signalstrength belonging to a second range.

The first range may include one of a preconfigured value, a valuetransferred as a Medium Access Control (MAC) Control Element (CE), avalue transferred by higher layer signaling, a value transferred byphysical layer signaling, a value selected by the remote UE, or a valueincluded in a discovery message.

The UE may communicate with at least one of another UE, a UE related toan autonomous vehicle, a base station, or a network

Advantageous Effects

According to one embodiment, service continuity may be maintained whilea relay is selected based on signal strength.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 is a diagram comparing vehicle-to-everything (V2X) communicationbased on pre-new radio access technology (pre-NR) with V2X communicationbased on NR;

FIG. 2 is a diagram illustrating the structure of a long term evolution(LTE) system according to an embodiment of the present disclosure;

FIG. 3 is a diagram illustrating user-plane and control-plane radioprotocol architectures according to an embodiment of the presentdisclosure:

FIG. 4 is a diagram illustrating the structure of an NR system accordingto an embodiment of the present disclosure;

FIG. 5 is a diagram illustrating functional split between a nextgeneration radio access network (NG-RAN) and a 5th generation corenetwork (5GC) according to an embodiment of the present disclosure;

FIG. 6 is a diagram illustrating the structure of an NR radio frame towhich embodiment(s) of the present disclosure is applicable:

FIG. 7 is a diagram illustrating a slot structure of an NR frameaccording to an embodiment of the present disclosure:

FIG. 8 is a diagram illustrating radio protocol architectures forsidelink (SL) communication according to an embodiment of the presentdisclosure:

FIG. 9 is a diagram illustrating radio protocol architectures for SLcommunication according to an embodiment of the present disclosure;

FIG. 10 illustrates a procedure in which a UE performs V2X or SLcommunication according to a transmission mode according to anembodiment of the present disclosure;

FIGS. 11 to 14 are diagrams to describe embodiment(s); and

FIGS. 15 to 21 are diagrams illustrating various devices to whichembodiment(s) may be applicable.

BEST MODE FOR DISCLOSURE

In various embodiments of the present disclosure, “/”and “,” should beinterpreted as “and/or”. For example, “A/B” may mean “A and/or B”.Further, “A. B” may mean “A and/or B”. Further, “A/B/C” may mean “atleast one of A, B and/or C”. Further, “A, B, C” may mean “at least oneof A, B and/or C”.

In various embodiments of the present disclosure, “or” should beinterpreted as “and/or”. For example, “A or B” may include “only A”,“only B”, and/or “both A and B”. In other words, “or” should beinterpreted as “additionally or alternatively”.

Techniques described herein may be used in various wireless accesssystems such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier-frequencydivision multiple access (SC-FDMA), and so on. CDMA may be implementedas a radio technology such as universal terrestrial radio access (UTRA)or CDMA2000. TDMA may be implemented as a radio technology such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA maybe implemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, evolved-UTRA (E-UTRA), or the like. IEEE802.16m is an evolution of IEEE 802.16e, offering backward compatibilitywith an IRRR 802.16e-based system. UTRA is a part of universal mobiletelecommunications system (UMTS). 3rd generation partnership project(3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS)using evolved UTRA (E-UTRA). 3GPP LTE employs OFDMA for downlink (DL)and SC-FDMA for uplink (UL). LTE-advanced (LTE-A) is an evolution of3GPP LTE.

A successor to LTE-A, 5th generation (5G) new radio access technology(NR) is a new clean-state mobile communication system characterized byhigh performance, low latency, and high availability. 5G NR may use allavailable spectral resources including a low frequency band below 1 GHz,an intermediate frequency band between 1 GHz and 10 GHz, and a highfrequency (millimeter) band of 24 GHz or above.

While the following description is given mainly in the context of LTE-Aor 5G NR for the clarity of description, the technical idea of anembodiment of the present disclosure is not limited thereto.

FIG. 2 illustrates the structure of an LTE system according to anembodiment of the present disclosure. This may also be called an evolvedUMTS terrestrial radio access network (E-UTRAN) or LTE/LTE-A system.

Referring to FIG. 2 , the E-UTRAN includes evolved Node Bs (eNBs) 20which provide a control plane and a user plane to UEs 10. A UE 10 may befixed or mobile, and may also be referred to as a mobile station (MS),user terminal (UT), subscriber station (SS), mobile terminal (MT), orwireless device. An eNB 20 is a fixed station communication with the UE10 and may also be referred to as a base station (BS), a basetransceiver system (BTS), or an access point.

eNBs 20 may be connected to each other via an X2 interface. An eNB 20 isconnected to an evolved packet core (EPC) 39 via an SI interface. Morespecifically, the eNB 20 is connected to a mobility management entity(MME) via an S1-MME interface and to a serving gateway (S-GW) via anS1-U interface.

The EPC 30 includes an MME, an S-GW, and a packet data network-gateway(P-GW). The MME has access information or capability information aboutUEs, which are mainly used for mobility management of the UEs. The S-GWis a gateway having the E-UTRAN as an end point, and the P-GW is agateway having a packet data network (PDN) as an end point.

Based on the lowest three layers of the open system interconnection(OSI) reference model known in communication systems, the radio protocolstack between a UE and a network may be divided into Layer 1 (L1), Layer2 (L2) and Layer 3 (L3). These layers are defined in pairs between a UEand an Evolved UTRAN (E-UTRAN), for data transmission via the Uuinterface. The physical (PHY) layer at L1 provides an informationtransfer service on physical channels. The radio resource control (RRC)layer at L3 functions to control radio resources between the UE and thenetwork. For this purpose, the RRC layer exchanges RRC messages betweenthe UE and an eNB.

FIG. 3(a) illustrates a user-plane radio protocol architecture accordingto an embodiment of the disclosure.

FIG. 3(b) illustrates a control-plane radio protocol architectureaccording to an embodiment of the disclosure. A user plane is a protocolstack for user data transmission, and a control plane is a protocolstack for control signal transmission.

Referring to FIGS. 3(a) and 3(b), the PHY layer provides an informationtransfer service to its higher layer on physical channels. The PHY layeris connected to the medium access control (MAC) layer through transportchannels and data is transferred between the MAC layer and the PHY layeron the transport channels. The transport channels are divided accordingto features with which data is transmitted via a radio interface.

Data is transmitted on physical channels between different PHY layers,that is, the PHY layers of a transmitter and a receiver. The physicalchannels may be modulated in orthogonal frequency division multiplexing(OFDM) and use time and frequencies as radio resources.

The MAC layer provides services to a higher layer, radio link control(RLC) on logical channels. The MAC layer provides a function of mappingfrom a plurality of logical channels to a plurality of transportchannels. Further, the MAC layer provides a logical channel multiplexingfunction by mapping a plurality of logical channels to a singletransport channel. A MAC sublayer provides a data transmission serviceon the logical channels.

The RLC layer performs concatenation, segmentation, and reassembly forRLC serving data units (SDUs). In order to guarantee various quality ofservice (QoS) requirements of each radio bearer (RB), the RLC layerprovides three operation modes, transparent mode (TM), unacknowledgedmode (UM), and acknowledged Mode (AM). An AM RLC provides errorcorrection through automatic repeat request (ARQ).

The RRC layer is defined only in the control plane and controls logicalchannels, transport channels, and physical channels in relation toconfiguration, reconfiguration, and release of RBs. An RB refers to alogical path provided by L1 (the PHY layer) and L2 (the MAC layer, theRLC layer, and the packet data convergence protocol (PDCP) layer), fordata transmission between the UE and the network.

The user-plane functions of the PDCP layer include user datatransmission, header compression, and ciphering. The control-planefunctions of the PDCP layer include control-plane data transmission andciphering/integrity protection.

RB establishment amounts to a process of defining radio protocol layersand channel features and configuring specific parameters and operationmethods in order to provide a specific service. RBs may be classifiedinto two types, signaling radio bearer (SRB) and data radio bearer(DRB). The SRB is used as a path in which an RRC message is transmittedon the control plane, whereas the DRB is used as a path in which userdata is transmitted on the user plane.

Once an RRC connection is established between the RRC layer of the UEand the RRC layer of the E-UTRAN, the UE is placed in RRC_CONNECTEDstate, and otherwise, the UE is placed in RRC_IDLE state. In NR,RRC_INACTIVE state is additionally defined. A UE in the RRC_INACTIVEstate may maintain a connection to a core network, while releasing aconnection from an eNB.

DL transport channels carrying data from the network to the UE include abroadcast channel (BCH) on which system information is transmitted and aDL shared channel (DL SCH) on which user traffic or a control message istransmitted. Traffic or a control message of a DL multicast or broadcastservice may be transmitted on the DL-SCH or a DL multicast channel (DLMCH). UL transport channels carrying data from the UE to the networkinclude a random access channel (RACH) on which an initial controlmessage is transmitted and an UL shared channel (UL SCH) on which usertraffic or a control message is transmitted.

The logical channels which are above and mapped to the transportchannels include a broadcast control channel (BCCH), a paging controlchannel (PCCH), a common control channel (CCCH), a multicast controlchannel (MCCH), and a multicast traffic channel (MTCH).

A physical channel includes a plurality of OFDM symbol in the timedomain by a plurality of subcarriers in the frequency domain. Onesubframe includes a plurality of OFDM symbols in the time domain. An RBis a resource allocation unit defined by a plurality of OFDM symbols bya plurality of subcarriers. Further, each subframe may use specificsubcarriers of specific OFDM symbols (e.g., the first OFDM symbol) in acorresponding subframe for a physical DL control channel (PDCCH), thatis, an L1/L2 control channel. A transmission time interval (TTI) is aunit time for subframe transmission.

FIG. 4 illustrates the structure of an NR system according to anembodiment of the present disclosure.

Referring to FIG. 4 , a next generation radio access network (NG-RAN)may include a next generation Node B (gNB) and/or an eNB, which providesuser-plane and control-plane protocol termination to a UE. In FIG. 4 ,the NG-RAN is shown as including only gNBs, by way of example. A gNB andan eNB are connected to each other via an Xn interface. The gNB and theeNB are connected to a 5G core network (5GC) via an NG interface. Morespecifically, the gNB and the eNB are connected to an access andmobility management function (AMF) via an NG-C interface and to a userplane function (UPF) via an NG-U interface.

FIG. 5 illustrates functional split between the NG-RAN and the 5GCaccording to an embodiment of the present disclosure.

Referring to FIG. 5 , a gNB may provide functions including inter-cellradio resource management (RRM), radio admission control, measurementconfiguration and provision, and dynamic resource allocation. The AMFmay provide functions such as non-access stratum (NAS) security andidle-state mobility processing. The UPF may provide functions includingmobility anchoring and protocol data unit (PDU) processing. A sessionmanagement function (SMF) may provide functions including UE Internetprotocol (IP) address allocation and PDU session control.

FIG. 6 illustrates a radio frame structure in NR, to which embodiment(s)of the present disclosure is applicable.

Referring to FIG. 6 , a radio frame may be used for UL transmission andDL transmission in NR. A radio frame is 10 ms in length, and may bedefined by two 5-ms half-frames. An HF may include five 1-ms subframes.A subframe may be divided into one or more slots, and the number ofslots in an SF may be determined according to a subcarrier spacing(SCS). Each slot may include 12 or 14 OFDM(A) symbols according to acyclic prefix (CP).

In a normal CP (NCP) case, each slot may include 14 symbols, whereas inan extended CP (ECP) case, each slot may include 12 symbols. Herein, asymbol may be an OFDM symbol (or CP-OFDM symbol) or an SC-FDMA symbol(or DFT-s-OFDM symbol).

Table 1 below lists the number of symbols per slot Nslotsymb, the numberof slots per frame Nframe,uslot, and the number of slots per subframeNsubframe,uslot according to an SCS configuration u in the NCP case.

TABLE 1 SCS (15*2u) N^(slot) _(symb) N^(frame, u) _(slot)N^(subframe, u) _(slot) 15 KHz (u = 0) 14 10 1 30 KHz (u = 1) 14 20 2 60KHz (u = 2) 14 40 4 120 KHz (u = 3) 14 80 8 240 KHz (u = 4) 14 160 16

Table 2 below lists the number of symbols per slot, the number of slotsper frame, and the number of slots per subframe according to an SCS inthe ECP case.

TABLE 2 SCS (15*2{circumflex over ( )}u) N^(slot) _(symb) N^(frame, u)_(slot) N^(subframe, u) _(slot) 60 KHz (u = 2) 12 40 4

In the NR system, different OFDM(A) numerologies (e.g., SCSs, CPlengths, and so on) may be configured for a plurality of cellsaggregated for one UE. Accordingly, the (absolute time) duration of atime resource including the same number of symbols (e.g., a subframe,slot, or TTI) (collectively referred to as a time unit (TU) forconvenience) may be configured to be different for the aggregated cells.

In NR, various numerologies or SCSs may be supported to support various5G services. For example, with an SCS of 15 kHz, a wide area intraditional cellular bands may be supported, while with an SCS of 30kHz/60 kHz, a dense urban area, a lower latency, and a wide carrierbandwidth may be supported. With an SCS of 60 kHz or higher, a bandwidthlarger than 24.25 GHz may be supported to overcome phase noise.

An NR frequency band may be defined by two types of frequency ranges,FR1 and FR2. The numerals in each frequency range may be changed. Forexample, the two types of frequency ranges may be given in [Table 3]. Inthe NR system. FR1 may be a “sub 6 GHz range” and FR2 may be an “above 6GHz range” called millimeter wave (mmW).

TABLE 3 Frequency Range Corresponding Subcarrier designation frequencyrange Spacing (SCS) FR1  450 MHz-6000 MHz  15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

As mentioned above, the numerals in a frequency range may be changed inthe NR system. For example, FR1 may range from 410 MHz to 7125 MHz aslisted in [Table 4]. That is, FR1 may include a frequency band of 6 GHz(or 5850, 5900, and 5925 MHz) or above. For example, the frequency bandof 6 GHz (or 5850, 5900, and 5925 MHz) or above may include anunlicensed band. The unlicensed band may be used for various purposes,for example, vehicle communication (e.g., autonomous driving).

TABLE 4 Frequency Range Corresponding Subcarrier designation frequencyrange Spacing (SCS) FR1  410 MHz-7125 MHz  15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

FIG. 7 illustrates a slot structure in an NR frame according to anembodiment of the present disclosure.

Referring to FIG. 7 , a slot includes a plurality of symbols in the timedomain. For example, one slot may include 14 symbols in an NCP case and12 symbols in an ECP case. Alternatively, one slot may include 7 symbolsin an NCP case and 6 symbols in an ECP case.

A carrier includes a plurality of subcarriers in the frequency domain.An RB may be defined by a plurality of (e.g., 12) consecutivesubcarriers in the frequency domain. A bandwidth part (BWP) may bedefined by a plurality of consecutive (physical) RBs ((P)RBs) in thefrequency domain and correspond to one numerology (e.g., SCS, CP length,or the like). A carrier may include up to N (e.g., 5) BWPs. Datacommunication may be conducted in an activated BWP. Each element may bereferred to as a resource element (RE) in a resource grid, to which onecomplex symbol may be mapped.

A radio interface between UEs or a radio interface between a UE and anetwork may include L1. L2, and L3. In various embodiments of thepresent disclosure, L1 may refer to the PHY layer. For example, L2 mayrefer to at least one of the MAC layer, the RLC layer, the PDCH layer,or the SDAP layer. For example, L3 may refer to the RRC layer.

Now, a description will be given of sidelink (SL) communication.

FIG. 8 illustrates a radio protocol architecture for SL communicationaccording to an embodiment of the present disclosure. Specifically, FIG.8(a) illustrates a user-plane protocol stack in LTE, and FIG. 8(b)illustrates a control-plane protocol stack in LTE.

FIG. 9 illustrates a radio protocol architecture for SL communicationaccording to an embodiment of the present disclosure. Specifically, FIG.9(a) illustrates a user-plane protocol stack in NR, and FIG. 9(b)illustrates a control-plane protocol stack in NR.

Resource allocation in SL will be described below.

FIG. 10 illustrates a procedure of performing V2X or SL communicationaccording to a transmission mode in a UE according to an embodiment ofthe present disclosure. In various embodiments of the presentdisclosure, a transmission mode may also be referred to as a mode or aresource allocation mode. For the convenience of description, atransmission mode in LTE may be referred to as an LTE transmission mode,and a transmission mode in NR may be referred to as an NR resourceallocation mode.

For example, FIG. 10(a) illustrates a UE operation related to LTEtransmission mode 1 or LTE transmission mode 3. Alternatively, forexample, FIG. 10(a) illustrates a UE operation related to NR resourceallocation mode 1. For example, LTE transmission mode 1 may be appliedto general SL communication, and LTE transmission mode 3 may be appliedto V2X communication.

For example, FIG. 10(b) illustrates a UE operation related to LTEtransmission mode 2 or LTE transmission mode 4. Alternatively, forexample, FIG. 10(b) illustrates a UE operation related to NR resourceallocation mode 2.

Referring to FIG. 10(a), in LTE transmission mode 1. LTE transmissionmode 3, or NR resource allocation mode 1, a BS may schedule SL resourcesto be used for SL transmission of a UE. For example, the BS may performresource scheduling for UE1 through a PDCCH (more specifically, DLcontrol information (DCI)), and UE1 may perform V2X or SL communicationwith UE2 according to the resource scheduling. For example, UE1 maytransmit sidelink control information (SCI) to UE2 on a PSCCH, and thentransmit data based on the SCI to UE2 on a PSSCH.

For example, in NR resource allocation mode 1, a UE may be provided withor allocated resources for one or more SL transmissions of one transportblock (TB) by a dynamic grant from the BS. For example, the BS mayprovide the UE with resources for transmission of a PSCCH and/or a PSSCHby the dynamic grant. For example, a transmitting UE may report an SLhybrid automatic repeat request (SL HARQ) feedback received from areceiving UE to the BS. In this case, PUCCH resources and a timing forreporting the SL HARQ feedback to the BS may be determined based on anindication in a PDCCH, by which the BS allocates resources for SLtransmission.

For example, the DCI may indicate a slot offset between the DCIreception and a first SL transmission scheduled by the DCI. For example,a minimum gap between the DCI that schedules the SL transmissionresources and the resources of the first scheduled SL transmission maynot be smaller than a processing time of the UE.

For example, in NR resource allocation mode 1, the UE may beperiodically provided with or allocated a resource set for a pluralityof SL transmissions through a configured grant from the BS. For example,the grant to be configured may include configured grant type 1 orconfigured grant type 2. For example, the UE may determine a TB to betransmitted in each occasion indicated by a given configured grant.

For example, the BS may allocate SL resources to the UE in the samecarrier or different carriers.

For example, an NR gNB may control LTE-based SL communication. Forexample, the NR gNB may transmit NR DCI to the UE to schedule LTE SLresources. In this case, for example, a new RNTI may be defined toscramble the NR DCI. For example, the UE may include an NR SL module andan LTE SL module.

For example, after the UE including the NR SL module and the LTE SLmodule receives NR SL DCI from the gNB, the NR SL module may convert theNR SL DCI into LTE DCI type 5A, and transmit LTE DCI type 5A to the LTESL module every Xms. For example, after the LTE SL module receives LTEDCI format 5A from the NR SL module, the LTE SL module may activateand/or release a first LTE subframe after Z ms. For example, X may bedynamically indicated by a field of the DCI. For example, a minimumvalue of X may be different according to a UE capability. For example,the UE may report a single value according to its UE capability. Forexample, X may be positive.

Referring to FIG. 10(b), in LTE transmission mode 2, LTE transmissionmode 4, or NR resource allocation mode 2, the UE may determine SLtransmission resources from among SL resources preconfigured orconfigured by the BS/network. For example, the preconfigured orconfigured SL resources may be a resource pool. For example, the UE mayautonomously select or schedule SL transmission resources. For example,the UE may select resources in a configured resource pool on its own andperform SL communication in the selected resources. For example, the UEmay select resources within a selection window on its own by a sensingand resource (re)selection procedure. For example, the sensing may beperformed on a subchannel basis. UE1, which has autonomously selectedresources in a resource pool, may transmit SCI to UE2 on a PSCCH andthen transmit data based on the SCI to UE2 on a PSSCH.

For example, a UE may help another UE with SL resource selection. Forexample, in NR resource allocation mode 2, the UE may be configured witha grant configured for SL transmission. For example, in NR resourceallocation mode 2, the UE may schedule SL transmission for another UE.For example, in NR resource allocation mode 2, the UE may reserve SLresources for blind retransmission.

For example, in NR resource allocation mode 2, UE1 may indicate thepriority of SL transmission to UE2 by SCI. For example, UE2 may decodethe SCI and perform sensing and/or resource (re)selection based on thepriority. For example, the resource (re)selection procedure may includeidentifying candidate resources in a resource selection window by UE2and selecting resources for (re)transmission from among the identifiedcandidate resources by UE2. For example, the resource selection windowmay be a time interval during which the UE selects resources for SLtransmission. For example, after UE2 triggers resource (re)selection,the resource selection window may start at T1≥0, and may be limited bythe remaining packet delay budget of UE2. For example, when specificresources are indicated by the SCI received from UE1 by the second UEand an L1 SL reference signal received power (RSRP) measurement of thespecific resources exceeds an SL RSRP threshold in the step ofidentifying candidate resources in the resource selection window by UE2,UE2 may not determine the specific resources as candidate resources. Forexample, the SL RSRP threshold may be determined based on the priorityof SL transmission indicated by the SCI received from UE1 by UE2 and thepriority of SL transmission in the resources selected by UE2.

For example, the L1 SL RSRP may be measured based on an SL demodulationreference signal (DMRS). For example, one or more PSSCH DMRS patternsmay be configured or preconfigured in the time domain for each resourcepool. For example, PDSCH DMRS configuration type 1 and/or type 2 may beidentical or similar to a PSSCH DMRS pattern in the frequency domain.For example, an accurate DMRS pattern may be indicated by the SCI. Forexample, in NR resource allocation mode 2, the transmitting UE mayselect a specific DMRS pattern from among DMRS patterns configured orpreconfigured for the resource pool.

For example, in NR resource allocation mode 2, the transmitting UE mayperform initial transmission of a TB without reservation based on thesensing and resource (re)selection procedure. For example, thetransmitting UE may reserve SL resources for initial transmission of asecond TB using SCI associated with a first TB based on the sensing andresource (re)selection procedure.

For example, in NR resource allocation mode 2, the UE may reserveresources for feedback-based PSSCH retransmission through signalingrelated to a previous transmission of the same TB. For example, themaximum number of SL resources reserved for one transmission, includinga current transmission, may be 2, 3 or 4. For example, the maximumnumber of SL resources may be the same regardless of whether HARQfeedback is enabled. For example, the maximum number of HARQ(re)transmissions for one TB may be limited by a configuration orpreconfiguration. For example, the maximum number of HARQ(re)transmissions may be up to 32. For example, if there is noconfiguration or preconfiguration, the maximum number of HARQ(re)transmissions may not be specified. For example, the configurationor preconfiguration may be for the transmitting UE. For example, in NRresource allocation mode 2. HARQ feedback for releasing resources whichare not used by the UE may be supported.

For example, in NR resource allocation mode 2, the UE may indicate oneor more subchannels and/or slots used by the UE to another UE by SCI.For example, the UE may indicate one or more subchannels and/or slotsreserved for PSSCH (re)transmission by the UE to another UE by SCI. Forexample, a minimum allocation unit of SL resources may be a slot. Forexample, the size of a subchannel may be configured or preconfigured forthe UE.

SCI will be described below.

While control information transmitted from a BS to a UE on a PDCCH isreferred to as DCI, control information transmitted from one UE toanother UE on a PSCCH may be referred to as SCI. For example, the UE mayknow the starting symbol of the PSCCH and/or the number of symbols inthe PSCCH before decoding the PSCCH. For example, the SCI may include SLscheduling information. For example, the UE may transmit at least oneSCI to another UE to schedule the PSSCH. For example, one or more SCIformats may be defined.

For example, the transmitting UE may transmit the SCI to the receivingUE on the PSCCH. The receiving UE may decode one SCI to receive thePSSCH from the transmitting UE.

For example, the transmitting UE may transmit two consecutive SCIs(e.g., 2-stage SCI) on the PSCCH and/or PSSCH to the receiving UE. Thereceiving UE may decode the two consecutive SCIs (e.g., 2-stage SCI) toreceive the PSSCH from the transmitting UE. For example, when SCIconfiguration fields are divided into two groups in consideration of a(relatively) large SCI payload size, SCI including a first SCIconfiguration field group is referred to as first SCI. SCI including asecond SCI configuration field group may be referred to as second SCI.For example, the transmitting UE may transmit the first SCI to thereceiving UE on the PSCCH. For example, the transmitting UE may transmitthe second SCI to the receiving UE on the PSCCH and/or PSSCH. Forexample, the second SCI may be transmitted to the receiving UE on an(independent) PSCCH or on a PSSCH in which the second SCI is piggybackedto data. For example, the two consecutive SCIs may be applied todifferent transmissions (e.g., unicast, broadcast, or groupcast).

For example, the transmitting UE may transmit all or part of thefollowing information to the receiving UE by SCI. For example, thetransmitting UE may transmit all or part of the following information tothe receiving UE by first SCI and/or second SCI.

-   -   PSSCH-related and/or PSCCH-related resource allocation        information, for example, the positions/number of time/frequency        resources, resource reservation information (e.g. a        periodicity), and/or    -   an SL channel state information (CSI) report request indicator        or SL (L1) RSRP (and/or SL (L1) reference signal received        quality (RSRQ) and/or SL (L1) received signal strength indicator        (RSSI)) report request indicator, and/or    -   an SL CSI transmission indicator (on PSSCH) (or SL (L1) RSRP        (and/or SL (L1) RSRQ and/or SL (L1) RSSI) information        transmission indicator), and/or    -   MCS information, and/or    -   transmission power information, and/or    -   L1 destination ID information and/or L1 source ID information,        and/or    -   SL HARQ process ID information, and/or    -   new data indicator (NDI) information, and/or    -   redundancy version (RV) information, and/or    -   QoS information (related to transmission traffic/packet), for        example, priority information, and/or    -   an SL CSI-RS transmission indicator or information about the        number of SL CSI-RS antenna ports (to be transmitted);    -   location information about a transmitting UE or location (or        distance area) information about a target receiving UE        (requested to transmit an SL HARQ feedback), and/or    -   RS (e.g., DMRS or the like) information related to decoding        and/or channel estimation of data transmitted on a PSSCH, for        example, information related to a pattern of (time-frequency)        mapping resources of the DMRS, rank information, and antenna        port index information.

For example, the first SCI may include information related to channelsensing. For example, the receiving UE may decode the second SCI usingthe PSSCH DMRS. A polar code used for the PDCCH may be applied to thesecond SCI. For example, the payload size of the first SCI may be equalfor unicast, groupcast and broadcast in a resource pool. After decodingthe first SCI, the receiving UE does not need to perform blind decodingon the second SCI. For example, the first SCI may include schedulinginformation about the second SCI.

In various embodiments of the present disclosure, since the transmittingUE may transmit at least one of the SCI, the first SCI, or the secondSCI to the receiving UE on the PSCCH, the PSCCH may be replaced with atleast one of the SCI, the first SCI, or the second SC. Additionally oralternatively, for example, the SCI may be replaced with at least one ofthe PSCCH, the first SCI, or the second SCI. Additionally oralternatively, for example, since the transmitting UE may transmit thesecond SCI to the receiving UE on the PSSCH, the PSSCH may be replacedwith the second SCI.

In side link communication, a discovery message may be used to set up aconnection with an adjacent UE. As illustrated in FIG. 11 , thediscovery message may be classified into Model A or Model B. The Model Ais a method in which an announcing UE continues to broadcast a discoverymessage and a monitoring UE listens to it, and the Model B is a methodin which when a discover UE broadcasts a discovery solicitation message,a discoveree UE sends a discovery message in response to it.

FIG. 12 illustrates a basic relationship between a UE-to-Network Relayand a UE-to-UE Relay. When a process of discovering each other by thetwo UEs is applied to a relay-related operation, it may be as follows.In the UE-to-Network Relay, a relay UE may be in a connection state witha gNB, and the relay UE may be in-coverage or out-of-coverage. When therelay UE broadcasts a discovery message (periodically), a remote UE mayhear it (Model A). If the remote UE broadcasts a solicitation message,the relay UE may broadcast/groupcast/unicast a discovery message inresponse to it (Model B).

The discovery message may include content as shown in Table 5, and fordetails, see TR 23.752.

TABLE 5 a) Application ID: An identity used by a UE to indicate aspecific ProSe application. The ProSe application ID is assigned(provided) by the ProSe application layer and can be used to identifye.g.: - An application e.g. Mission Critical Voice, Game A, Game B, TaxiCommunications company Y b) Destination Layer-2 ID Indicate: - Aspecific target UE layer-2 ID or layer-2 ID for initial signalling. c)Source Layer-2 ID that is set to a unicast identifier of thetransmitter. d) Source UE's ProSe Application Layer ID. An identity usedto identify the source ProSe UE at the application layer. It is providedby the ProSe Application Layer to the ProSe Layer. e) Target UE's ProSeApplication Layer ID. An identity used to identify the destination ProSeUE at the application layer. It is provided by the ProSe ApplicationLayer to the ProSe Layer. f) ProSe Application Layer Group ID. Anidentity used to identify a application layer group the UE belongs to.g) Relay Service Code (for UE-to-Network Relay Discovery): - RelayService Code as defined in TS 23.303 [9]. h) Discovery Group ID (forGroup Member Discovery): - Discovery Group ID as defined in TS 23.303[9]. All of the above identities can be either fixed over time or can bedynamic depending on operator configuration. When an identity isdynamic, it will have a validity timer. Dynamic allocation of theidentities by the ProSe Application layer allows for privacy support.

Hereinafter, based on the above description, a method of selecting arelay UE by a remote UE in a side link relay-related operation,transmission and reception of a discovery message in association withdelivery of information related to this selection, contents that may beincluded in the discovery message, etc. will be described.

A remote UE according to one embodiment may select at least one or morecandidate relay UEs, and the remote UE may select a relay UE from the atleast one or more candidate relay UEs.

Here, the selection of the one or more candidate relay UEs is based onsidelink signal strength of each candidate relay UE, and the selectionof the relay UE may be based on the comparison of a cell ID selectedaccording to cell ID and Uu link signal strength of each of thecandidate relay UEs. The relay UE has the same cell ID as the cell IDselected according to the Uu link signal strength.

The cell ID selected according to the Uu link signal strength may be anID of a cell having a signal strength of a first threshold or more amongthe Uu link signals measured by the relay. Alternatively, the cell IDselected according to the Uu link signal strength may be an ID of a cellin which the Uu link signal strength measured by the relay belongs to afirst range. Similarly, the at least one candidate relay UE may have asidelink signal strength greater than or equal to a second thresholdvalue, or the at least one candidate relay UE may have a sidelink signalstrength within a second range. References of the Uu link signalstrength and the sidelink signal strength may be used in a combinedform. For example, one of (first threshold, second threshold), (firstthreshold, first range), (first range, second threshold), and (firstrange, second threshold) may be used as a reference for (Uu link signalstrength, sidelink signal strength). There may be a plurality of cellIDs or relay UEs that satisfy each threshold or range, and in this case,side link signal strength may be considered more preferentially. Thatis, when there are a plurality of candidate relay UEs having the samecell ID as the cell ID selected according to the Uu link signalstrength, the remote UE may consider the sidelink signal strength morepreferentially.

The above description may be described as follows. The remote UEextracts a candidate relay UE based on sidelink signal strength (e.g.,when the sidelink signal strength falls within a predetermined range).In addition, the remote UE measures Uu direct signal strength andextracts a cell ID whose measurement value falls within a prescribedthreshold value or more (or a specified range). Furthermore, the remoteUE selects its own relay UE based on the result of a cell ID of thecandidate relay UE extracted through the sidelink signal strength andthe cell ID extracted through the Uu direct link signal strength. Inother words, when the cell ID to which the relay UE belongs has the samecell ID as the cell ID extracted through the Uu direct link measured bythe remote UE, the relay UE is selected preferentially.

The first range may be one of a preset value, a value transferredthrough a Medium Access Control (MAC) Control Element (CE), a valuetransferred through a higher layer signaling, a value transferredthrough physical layer signaling, a value selected by the remote UE, anda value included in a discovery message.

When the relay UE is selected as described above, the remote UE mayobtain a gain in terms of service continuity. Specifically, referring toFIG. 13 , a remote UE may select relay UEs A and B as candidate relaysbased on sidelink signal strength. In addition, based on Uu link signalstrengths of a gNB A and a gNB B, the remote UE selects the gNB B.Comparing a cell ID of the candidate relay UE with a cell ID selectedbased on the selected Uu link signal strength, the cell ID of the gNB Bis common, so the remote UE selects the relay UE B as the relay UE. Asillustrated in FIG. 13 , sidelink signal strength of the relay UE B issmaller than that of the relay UE A, but the relay UE B selected by theabove method belongs to the same gNB B of the remote UE. Accordingly,the remote UE may continuously receive a service from the gNB B withouta handover even if relay communication with the relay UE B isinterrupted.

In other words, the relay UE may perform a path switch (directpath→indirect, indirect→direct) in some cases, and if the relay UEbelongs to a different cell, it should perform a Hand Over (HO) tomaintain the service continuity. Since an HO process requires anoperation process for this, frequent HOs may burden the remote UE.Therefore, when the remote UE performs the path switch, if the pathswitch is performed within the same cell, the path switch is possiblewithout the HO process, so the service continuity is available without aprocess overhead due to the HO.

As another example, the remote UE measures all direct path (Uu link)signal strengths (e.g., RSRP/RSRQ/RSNR) that it can measure. In thiscase, a cell ID of the direct path whose measured direct path signalstrength is equal to or greater than a determined threshold isextracted. From relay UEs belonging to the extracted cell ID, acandidate relay UE is selected based on a sidelink signal strength(e.g., when the sidelink signal strength falls within a predeterminedrange). In this case, a size of a threshold for filtering a Uu path anda sidelink signal reference value are the values that can be transmittedusing predefined values. RRC, MAC CE, etc.

Namely, a cell is primarily selected with a direct path (Uu link) signalstrength, and is secondarily selected with a sidelink signal strengthfrom relays belonging to the cell. In this case, there is an advantagethat only relay signals of relays included in the selected cell need tobe measured. The proposed method has the advantage of being able toselect a relay UE having the most stable (best) side link signalstrength in consideration of service continuity, in that it is possibleto primarily select a relay UE with the best sidelink signal strengthfrom candidate relay UEs belonging to a cell ID group having Uu directlink signal strength equal to or greater than a predetermined value.

In the above description, the direct path represents a path that can bedirectly connected to a Uu, and an indirect path represents a path thatcan be indirectly connected to a base station through a relay. In thiscase, ‘measuring a signal strength of a direct path’ means signalstrengths of all cells that can be measured by the remote UEirrespective of RRC status (CONNECTED/IDLE/INACTIVE) state and a cell onwhich the remote UE camps.

Meanwhile, in the above description, the cell ID may be included in thediscovery message. As described above, the discovery message may includeinformation related to sidelink relay communication, which will bedescribed in detail below.

As mentioned, the discovery message may include a cell ID (information).The relay UE and/or the remote UE may include cell identifierinformation of a cell with which the corresponding UE sets upconnection, camping cell identifier information of a camping cell towhich the corresponding UE belongs (in coverage aspect), and/or the likein Discovery/Solicitation/Discovery Response Message transmitted by thecorresponding UE. Alternatively, the corresponding operation may belimited to a solicitation message (and/or a response message). Inaddition, this method may be extended and applied as discovery messageconfiguration information transmitted by the remote UE.

For example, when transmitting a discovery message, a relay UE maytransmit the message in a manner that cell identifier information of acell with which the corresponding UE sets up connection, camping cellidentifier information of a camping cell to which the corresponding UEbelongs (in coverage aspect), and/or the like is included in thediscovery message. Having received the discovery message, a remote UEmay preferentially select a relay UE with the same cell ID of a cellwith which the remote UE sets up connection (if the remote UE isin-coverage) [Discovery Model A].

Alternatively, when transmitting a solicitation message, a remote UE maytransmit the message in a manner that cell identifier information of acell with which the corresponding UE sets up connection, camping cellidentifier information of a camping cell to which the corresponding UEbelongs (in coverage aspect), and/or the like is included in thesolicitation message (if the remote UE is in-coverage). When a candidaterelay UE having received the message has the same cell identifierinformation as the remote UE and/or only if the camping cell identifierinformation of the camping cell to which the remote UE belongs isincluded, the candidate relay UE may transmit a response message.

Alternatively, when transmitting a solicitation message, a remote UE maytransmit the message in a manner that cell identifier information of acell with which the corresponding UE sets up connection, camping cellidentifier information of a camping cell to which the corresponding UEbelongs (in coverage aspect), and/or the like is included in thesolicitation message (if the remote UE is in-coverage). And, a candidaterelay UE having received the message may also transmit a messageincluding cell identifier information of a cell with which thecorresponding UE sets up connection, camping cell identifier informationof a camping cell to which the corresponding UE belongs (in coverageaspect), and/or the like. In this case, the remote UE having received aresponse message including the corresponding information may select arelay UE advantageous (e.g., same cell ID, camping cell informationoverlapping case, etc.) for the remote UE from candidate relay UEshaving sent the responses.

Alternatively, a remote UE transmits a solicitation message and a relayUE may then transmits a message including cell identifier information ofa cell with which the corresponding UE sets up connection, camping cellidentifier information of a camping cell to which the corresponding UEbelongs (in coverage aspect), and/or the like in response to thesolicitation message. In this case, the remote UE may select a relay UEhaving sent a response including the same identification information asthe cell identifier information of the cell with which the relay UE setsup connection, or may preferentially select a connection with a relay UEincluding cell identifier information of a cell on which the remote UEcan camp.

The corresponding message may be included in a discovery messagecontent, an SIC/NAC header, etc.

In addition, a discovery message may include information on whether Uulink RRC Connection is present. In (UE-to-Network/UE-to-UE) relaycommunication, the discovery message is usually broadcasted by a relayUE. In this case, the relay UE indicates a Uu link connection state witha base station in a manner of including it in the discovery message(Discovery Model A). Alternatively, when a remote UE broadcasts asolicitation message, the remote message may send the solicitationmessage including the Uu link RRC connected state of the remote UE.Alternatively, when the relay UE delivers a discovery message inresponse to the solicitation message of the remote UE, it may transmitthe message in a manner of including the RRC connected state in thediscovery message in response (Discovery Model B).

In this case, only ‘whether it is in the RRC connected state’ may beindicated, or the RRC CONNECTION state (e.g., IDLE, INACTIVE.CONNECTION) may be directly indicated. The Uu link RRC Connectioninformation may be the information included in the discovery message, ormay be a value transmitted through an SCI/MAC header when transmittingthe discovery message.

Upon receiving this, the remote UE may preferentially select a relay UEthat is in the ‘RRC CONNECTED state’ from the candidate relay UEs whenselecting a relay. In this case, the candidate relay UE refers to a UEin which a sidelink signal strength between the remote UE and the relayUE corresponds to a predetermined threshold range. When selecting arelay UE that is in the ‘RRC CONNECTED state’, it is possible to reducethe time taken for the relay UE and the base station to set up aconnection, thereby reducing the latency for transmitting initial data.

Subsequently, multi-hop number information may be included in thediscovery message. In order to expand to a multi-hop operation of asidelink relay in the future, the discovery message may include thenumber of multi-hops and be then transmitted. Multi-hop information maybe transmitted through contents of the discovery message, or may be avalue transmitted through the SCI/MAC header that transmits thediscovery message.

Upon receiving this, the remote UE may preferentially select a relay UEwith a small multi-hop number when selecting a relay to use for datatransmission from candidate relays. When selecting a relay UE with asmall number of multi-hops, it corresponds to a case that the number ofhops to a destination (e.g., a base station in UE-to-Network) is small,whereby it may be advantageous in terms of latency/reliability used fordata transmission.

Zone-ID/MCR information may also be included in the discovery message.When the discovery message is transmitted, it may be transmitted in amanner of including zone-ID and Minimum Communication Range (MCR)information. A range in which the relay UE plays a relay role reliablymay be determined through the zone-ID and the MCR information.Meanwhile, since a range of a transmit power value of the relay UE maybe adjusted through this, it may be helpful for the power saving of therelay UE as well.

Upon receiving this, the remote UE may select a UE having good signalstrength from candidate relay UEs belonging to an MCR range in selectinga relay UE (Discovery Model A). Alternatively, the relay UE may send adiscovery message response only to a remote UE within the MCR range(Discovery Model B).

In addition, the discovery message may also include relay type(UE-to-Network Relay (UE-to-UE Relay)) information. A relay type capableof relay or a desired relay type may be indicated in the discoverymessage (e.g., discovery, solicitation, response message, etc.). Forexample, a discovery message for a UE-to-Network Relay may be marked as‘0’ and a discovery message for a UE-to-UE Relay may be marked as ‘1’.

In case of Discovery Model A, a relay UE capable of performing UE-to-UERelay may broadcast a discovery message including an ID (e.g.,MAC/service/ProSe/application ID) (list) of another UE currentlyconnected to the relay UE or recognizable by the relay UE itself despiteno connection setup together with an indication indicating that therelay UE can play a UE-to-UE Relay role. Upon receiving thecorresponding message, a UE desiring the relay may select a relay UEannouncing that it can connect to a target UE that the corresponding UEwants to communicate with.

Alternatively, in case of Discovery Model B, for example, when sending asolicitation message to find a relay UE for UE-to-UE Relay, a UE maysending the message including an ID of a target UE (list) thecorresponding UE wants to set up connection with together with anindication indicating that the corresponding UE is looking for UE-to-UERelay. Upon receiving the corresponding solicitation message, acandidate relay UE sends a response (/discovery) message only if it iscapable of setting up a connection with the target UE (list) included inthe solicitation message (determined based on RSRP)/it is alreadyconnected thereto.

The information included in the discovery message may also betransmitted through SIC/MAC header/MAC CE of a physical layer.

Hereinafter, in case of Discovery Model B, a method of reducing latencydespite operating using a discovery resource pool will be described. Inthe following description, assuming that a discovery message is appliedto relay communication, a discoverer UE transmitting a solicitationmessage is assumed as a remote UE and a discoveree UE transmitting aresponse message in response to it is assumed as a relay UE. Of course,the proposed disclosure contents may be applied to a general discoveryprocess between sidelink UEs. The following description is applicable tothe case of Discovery Model B.

A remote UE may broadcast/groupcast a solicitation message on a(pre-)configured discovery resource pool and/or a discovery resourcepool configured via RRC. Upon receiving it, a relay UE may send aresponse message to the remote UE, but if there is no suitable resourcein a discovery resource pool interval in which the solicitation messagewas sent, a response message should be sent on a discovery resource poolin a next periodicity. When operating in this way, it may take a lot oflatency to detect each other. Therefore, a method proposed in anembodiment is a method of sending a solicitation message on a discoveryresource pool but sending a response message in response to thesolicitation message on a general communication resource.

FIG. 14 (a) illustrates an operation according to a related art.Referring to FIG. 14 , when discovery resource pools are periodicallyconfigured, a discovery resource pool for transmitting a solicitationmessage and a discovery resource pool for transmitting a responsemessage in response to it may be different from each other. In thiscase, it may take time for a remote UE and a relay UE to detect eachother by a time interval of a next discovery resource pool.

FIG. 14 (b) illustrates an operation according to an embodiment. Aremote UE transmits a solicitation message on a discovery resource poolin a manner that a time interval in which the remote UE is scheduled toexist in a wake-up state even after a discovery resource pool intervalis included in a discovery message. Alternatively, a predetermined timefor wake-up may be pre-configured even after the discovery message poolis completed after sending the solicitation message. Since a relay UEhaving received it or a (pre-)configured relay UE is aware of a timeinterval during which the corresponding remote UE wakes up, it may senda response message in the corresponding interval. In this case, theresponse message is transmitted through a general communication resourcepool. In case of applying the corresponding method, the relay UE onlyneeds to monitor a discovery resource pool as before, and the remote UEalso transmits a solicitation message on the discovery resource poolonly, so a power saving operation is possible to detect each other.However, it is possible to reduce the latency that may occur over theperiodicity of the discovery resource pool by enabling the response tothe solicitation message to be made through a general communicationresource. In addition, by configuring a time for the remote UE to waitfor the response message in the solicitation message, the remote UE isalso in a wake-up state only for a time to wait for the response messagedelivered through the communication resource, whereby a power savingoperation is available as well. The wake-up time configured by theremote UE may be valid only in the same interval as a frequency axis ofthe discovery resource pool.

The proposed method is summarized as follows.

-   -   1. A solicitation message is broadcasted on a discovery resource        pool.    -   2. An additional time in which a corresponding UE wakes up even        after expiration of a discovery resource pool interval may be        configured in the solicitation message. Alternatively, an        additional wake-up time may be configured in a relay/remote UE        for a predetermined time after the discovery resource pool on        which the solicitation message was sent ends.    -   3. A UE that transmits a response message may transmit the        response message on a discovery resource pool in a time interval        included in a solicitation message (and/or a (pre-)configured        time interval). In this case, the response message may be        transmitted using a general communication resource pool.    -   4. A frequency-axis interval available for the response message        transmitted using the general communication resource pool is the        same as a frequency-axis interval in which an existing discovery        resource pool is configured.

It is a matter of course that the above-described methods are applicablealone or in combination of several methods. In addition, the contents ofthe present disclosure is equally applicable to both a relay UE and aremote UE.

Examples of Communication Systems Applicable to the Present Disclosure

The various descriptions, functions, procedures, proposals, methods,and/or operational flowcharts of the present disclosure described inthis document may be applied to, without being limited to, a variety offields requiring wireless communication/connection (e.g., 5G) betweendevices.

Hereinafter, a description will be given in more detail with referenceto the drawings. In the following drawings/description, the samereference symbols may denote the same or corresponding hardware blocks,software blocks, or functional blocks unless described otherwise.

FIG. 15 illustrates a communication system 1 applied to the presentdisclosure.

Referring to FIG. 15 , a communication system 1 applied to the presentdisclosure includes wireless devices, BSs, and a network. Herein, thewireless devices represent devices performing communication using RAT(e.g., 5G NR or LTE) and may be referred to as communication/radio/5Gdevices. The wireless devices may include, without being limited to, arobot 100 a, vehicles 100 b-1 and 100 b-2, an extended reality (XR)device 100 c, a hand-held device 100 d, a home appliance 100 e, anInternet of things (IoT) device 100 f, and an artificial intelligence(AI) device/server 400. For example, the vehicles may include a vehiclehaving a wireless communication function, an autonomous driving vehicle,and a vehicle capable of performing communication between vehicles.Herein, the vehicles may include an unmanned aerial vehicle (UAV) (e.g.,a drone). The XR device may include an augmented reality (AR)/virtualreality (VR)/mixed reality (MR) device and may be implemented in theform of a head-mounted device (HMD), a head-up display (HUD) mounted ina vehicle, a television, a smartphone, a computer, a wearable device, ahome appliance device, a digital signage, a vehicle, a robot, etc. Thehand-held device may include a smartphone, a smartpad, a wearable device(e.g., a smartwatch or a smartglasses), and a computer (e.g., anotebook). The home appliance may include a TV, a refrigerator, and awashing machine. The IoT device may include a sensor and a smartmeter.For example, the BSs and the network may be implemented as wirelessdevices and a specific wireless device 200 a may operate as a BS/networknode with respect to other wireless devices.

The wireless devices 100 a to 100 f may be connected to the network 300via the BSs 200. An AI technology may be applied to the wireless devices100 a to 100 f and the wireless devices 100 a to 100 f may be connectedto the AI server 400 via the network 300. The network 300 may beconfigured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g.,NR) network. Although the wireless devices 100 a to 100 f maycommunicate with each other through the BSs 200/network 300, thewireless devices 100 a to 100 f may perform direct communication (e.g.,sidelink communication) with each other without passing through theBSs/network. For example, the vehicles 100 b-1 and 100 b-2 may performdirect communication (e.g. V2/V2X communication). The IoT device (e.g.,a sensor) may perform direct communication with other IoT devices (e.g.,sensors) or other wireless devices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, or 150 c may beestablished between the wireless devices 100 a to 100 f/BS 200, or BS200/BS 200. Herein, the wireless communication/connections may beestablished through various RATs (e.g., 5G NR) such as UL/DLcommunication 150 a, sidelink communication 150 b (or, D2Dcommunication), or inter BS communication (e.g. relay, integrated accessbackhaul (IAB)). The wireless devices and the BSs/the wireless devicesmay transmit/receive radio signals to/from each other through thewireless communication/connections 150 a and 150 b. For example, thewireless communication/connections 150 a and 150 b may transmit/receivesignals through various physical channels. To this end, at least a partof various configuration information configuring processes, varioussignal processing processes (e.g., channel encoding/decoding,modulation/demodulation, and resource mapping/demapping), and resourceallocating processes, for transmitting/receiving radio signals, may beperformed based on the various proposals of the present disclosure.

Examples of Wireless Devices Applicable to the Present Disclosure

FIG. 16 illustrates wireless devices applicable to the presentdisclosure.

Referring to FIG. 16 , a first wireless device 100 and a second wirelessdevice 200 may transmit radio signals through a variety of RATs (e.g.,LTE and NR). Herein, {the first wireless device 100 and the secondwireless device 200} may correspond to {the wireless device 100 x andthe BS 200} and/or {the wireless device 100 x and the wireless device100 x} of FIG. 15 .

The first wireless device 100 may include one or more processors 102 andone or more memories 104 and additionally further include one or moretransceivers 106 and/or one or more antennas 108. The processor(s) 102may control the memory(s) 104 and/or the transceiver(s) 106 and may beconfigured to implement the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument. For example, the processor(s) 102 may process informationwithin the memory(s) 104 to generate first information/signals and thentransmit radio signals including the first information/signals throughthe transceiver(s) 106. The processor(s) 102 may receive radio signalsincluding second information/signals through the transceiver 106 andthen store information obtained by processing the secondinformation/signals in the memory(s) 104. The memory(s) 104 may beconnected to the processor(s) 102 and may store a variety of informationrelated to operations of the processor(s) 102. For example, thememory(s) 104 may store software code including commands for performinga part or the entirety of processes controlled by the processor(s) 102or for performing the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.Herein, the processor(s) 102 and the memory(s) 104 may be a part of acommunication modem/circuit/chip designed to implement RAT (e.g., LTE orNR). The transceiver(s) 106 may be connected to the processor(s) 102 andtransmit and/or receive radio signals through one or more antennas 108.Each of the transceiver(s) 106 may include a transmitter and/or areceiver. The transceiver(s) 106 may be interchangeably used with RadioFrequency (RF) unit(s). In the present disclosure, the wireless devicemay represent a communication modem/circuit/chip.

The second wireless device 200 may include one or more processors 202and one or more memories 204 and additionally further include one ormore transceivers 206 and/or one or more antennas 208. The processor(s)202 may control the memory(s) 204 and/or the transceiver(s) 206 and maybe configured to implement the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument. For example, the processor(s) 202 may process informationwithin the memory(s) 204 to generate third information/signals and thentransmit radio signals including the third information/signals throughthe transceiver(s) 206. The processor(s) 202 may receive radio signalsincluding fourth information/signals through the transceiver(s) 106 andthen store information obtained by processing the fourthinformation/signals in the memory(s) 204. The memory(s) 204 may beconnected to the processor(s) 202 and may store a variety of informationrelated to operations of the processor(s) 202. For example, thememory(s) 204 may store software code including commands for performinga part or the entirety of processes controlled by the processor(s) 202or for performing the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.Herein, the processor(s) 202 and the memory(s) 204 may be a part of acommunication modem/circuit/chip designed to implement RAT (e.g., LTE orNR). The transceiver(s) 206 may be connected to the processor(s) 202 andtransmit and/or receive radio signals through one or more antennas 208.Each of the transceiver(s) 206 may include a transmitter and/or areceiver. The transceiver(s) 206 may be interchangeably used with RFunit(s). In the present disclosure, the wireless device may represent acommunication modem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 willbe described more specifically. One or more protocol layers may beimplemented by, without being limited to, one or more processors 102 and202. For example, the one or more processors 102 and 202 may implementone or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP,RRC, and SDAP). The one or more processors 102 and 202 may generate oneor more Protocol Data Units (PDUs) and/or one or more service data unit(SDUs) according to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document. Theone or more processors 102 and 202 may generate messages, controlinformation, data, or information according to the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document. The one or more processors 102 and 202 maygenerate signals (e.g., baseband signals) including PDUs, SDUs,messages, control information, data, or information according to thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document and provide thegenerated signals to the one or more transceivers 106 and 206. The oneor more processors 102 and 202 may receive the signals (e.g., basebandsignals) from the one or more transceivers 106 and 206 and acquire thePDUs, SDUs, messages, control information, data, or informationaccording to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. As an example, one or moreapplication specific integrated circuits (ASICs), one or more digitalsignal processors (DSPs), one or more digital signal processing devices(DSPDs), one or more programmable logic devices (PLDs), or one or morefield programmable gate arrays (FPGAs) may be included in the one ormore processors 102 and 202. The descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument may be implemented using firmware or software and the firmwareor software may be configured to include the modules, procedures, orfunctions. Firmware or software configured to perform the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document may be included in the one or more processors102 and 202 or stored in the one or more memories 104 and 204 so as tobe driven by the one or more processors 102 and 202. The descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document may be implemented using firmware or softwarein the form of code, commands, and/or a set of commands.

The one or more memories 104 and 204 may be connected to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories 104 and 204 may be configured by read-onlymemories (ROMs), random access memories (RAMs), electrically erasableprogrammable read-only memories (EPROMs), flash memories, hard drives,registers, cash memories, computer-readable storage media, and/orcombinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be connected tothe one or more processors 102 and 202 through various technologies suchas wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or radio signals/channels, mentioned in the methodsand/or operational flowcharts of this document, to one or more otherdevices. The one or more transceivers 106 and 206 may receive user data,control information, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, from one or moreother devices. For example, the one or more transceivers 106 and 206 maybe connected to the one or more processors 102 and 202 and transmit andreceive radio signals. For example, the one or more processors 102 and202 may perform control so that the one or more transceivers 106 and 206may transmit user data, control information, or radio signals to one ormore other devices. The one or more processors 102 and 202 may performcontrol so that the one or more transceivers 106 and 206 may receiveuser data, control information, or radio signals from one or more otherdevices. The one or more transceivers 106 and 206 may be connected tothe one or more antennas 108 and 208 and the one or more transceivers106 and 206 may be configured to transmit and receive user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, through the one ormore antennas 108 and 208. In this document, the one or more antennasmay be a plurality of physical antennas or a plurality of logicalantennas (e.g., antenna ports). The one or more transceivers 106 and 206may convert received radio signals/channels etc. from RF band signalsinto baseband signals in order to process received user data, controlinformation, radio signals/channels, etc. using the one or moreprocessors 102 and 202. The one or more transceivers 106 and 206 mayconvert the user data, control information, radio signals/channels, etc.processed using the one or more processors 102 and 202 from the baseband signals into the RF band signals. To this end, the one or moretransceivers 106 and 206 may include (analog) oscillators and/orfilters.

Examples of a Vehicle or an Autonomous Driving Vehicle Applicable to thePresent Disclosure

FIG. 17 illustrates a vehicle or an autonomous driving vehicle appliedto the present disclosure. The vehicle or autonomous driving vehicle maybe implemented by a mobile robot, a car, a train, a manned/unmannedaerial vehicle (AV), a ship, etc.

Referring to FIG. 17 , a vehicle or autonomous driving vehicle 100 mayinclude an antenna unit 108, a communication unit 110, a control unit120, a driving unit 140 a, a power supply unit 140 b, a sensor unit 140c, and an autonomous driving unit 140 d. The antenna unit 108 may beconfigured as a part of the communication unit 110.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from external devices such as othervehicles, BSs (e.g., gNBs and road side units), and servers. The controlunit 120 may perform various operations by controlling elements of thevehicle or the autonomous driving vehicle 100. The control unit 120 mayinclude an ECU. The driving unit 140 a may cause the vehicle or theautonomous driving vehicle 100 to drive on a road. The driving unit 140a may include an engine, a motor, a powertrain, a wheel, a brake, asteering device, etc. The power supply unit 140 b may supply power tothe vehicle or the autonomous driving vehicle 100 and include awired/wireless charging circuit, a battery, etc. The sensor unit 140 cmay acquire a vehicle state, ambient environment information, userinformation, etc. The sensor unit 140 c may include an inertialmeasurement unit (IMU) sensor, a collision sensor, a wheel sensor, aspeed sensor, a slope sensor, a weight sensor, a heading sensor, aposition module, a vehicle forward/backward sensor, a battery sensor, afuel sensor, a tire sensor, a steering sensor, a temperature sensor, ahumidity sensor, an ultrasonic sensor, an illumination sensor, a pedalposition sensor, etc. The autonomous driving unit 140 d may implementtechnology for maintaining a lane on which a vehicle is driving,technology for automatically adjusting speed, such as adaptive cruisecontrol, technology for autonomously driving along a determined path,technology for driving by automatically setting a path if a destinationis set, and the like.

For example, the communication unit 110 may receive map data, trafficinformation data, etc. from an external server. The autonomous drivingunit 140 d may generate an autonomous driving path and a driving planfrom the obtained data. The control unit 120 may control the drivingunit 140 a such that the vehicle or the autonomous driving vehicle 100may move along the autonomous driving path according to the driving plan(e.g., speed/direction control). In the middle of autonomous driving,the communication unit 110 may aperiodically/periodically acquire recenttraffic information data from the external server and acquiresurrounding traffic information data from neighboring vehicles. In themiddle of autonomous driving, the sensor unit 140 c may obtain a vehiclestate and/or surrounding environment information. The autonomous drivingunit 140 d may update the autonomous driving path and the driving planbased on the newly obtained data/information. The communication unit 110may transfer information about a vehicle position, the autonomousdriving path, and/or the driving plan to the external server. Theexternal server may predict traffic information data using AItechnology, etc., based on the information collected from vehicles orautonomous driving vehicles and provide the predicted trafficinformation data to the vehicles or the autonomous driving vehicles.

Examples of a Vehicle and AR/VR Applicable to the Present Disclosure

FIG. 18 illustrates a vehicle applied to the present disclosure. Thevehicle may be implemented as a transport means, an aerial vehicle, aship, etc.

Referring to FIG. 18 , a vehicle 100 may include a communication unit110, a control unit 120, a memory unit 130, an I/O unit 140 a, and apositioning unit 140 b.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from external devices such as other vehiclesor BSs. The control unit 120 may perform various operations bycontrolling constituent elements of the vehicle 100. The memory unit 130may store data/parameters/programs/code/commands for supporting variousfunctions of the vehicle 100. The 110 unit 140 a may output an AR/VRobject based on information within the memory unit 130. The I/O unit 140a may include an HUD. The positioning unit 140 b may acquire informationabout the position of the vehicle 100. The position information mayinclude information about an absolute position of the vehicle 100,information about the position of the vehicle 100 within a travelinglane, acceleration information, and information about the position ofthe vehicle 100 from a neighboring vehicle. The positioning unit 140 bmay include a GPS and various sensors.

As an example, the communication unit 110 of the vehicle 100 may receivemap information and traffic information from an external server andstore the received information in the memory unit 130. The positioningunit 140 b may obtain the vehicle position information through the GPSand various sensors and store the obtained information in the memoryunit 130. The control unit 120 may generate a virtual object based onthe map information, traffic information, and vehicle positioninformation and the I/O unit 140 a may display the generated virtualobject in a window in the vehicle (1410 and 1420). The control unit 120may determine whether the vehicle 100 normally drives within a travelinglane, based on the vehicle position information. If the vehicle 100abnormally exits from the traveling lane, the control unit 120 maydisplay a warning on the window in the vehicle through the I/O unit 140a. In addition, the control unit 120 may broadcast a warning messageregarding driving abnormity to neighboring vehicles through thecommunication unit 110. According to situation, the control unit 120 maytransmit the vehicle position information and the information aboutdriving/vehicle abnormality to related organizations.

Examples of an XR Device Applicable to the Present Disclosure

FIG. 19 illustrates an XR device applied to the present disclosure. TheXR device may be implemented by an HMD, an HUD mounted in a vehicle, atelevision, a smartphone, a computer, a wearable device, a homeappliance, a digital signage, a vehicle, a robot, etc.

Referring to FIG. 19 , an XR device 100 a may include a communicationunit 110, a control unit 120, a memory unit 130, an I/O unit 140 a, asensor unit 140 b, and a power supply unit 140 c.

The communication unit 110 may transmit and receive signals (e.g., mediadata and control signals) to and from external devices such as otherwireless devices, hand-held devices, or media servers. The media datamay include video, images, and sound. The control unit 120 may performvarious operations by controlling constituent elements of the XR device100 a. For example, the control unit 120 may be configured to controland/or perform procedures such as video/image acquisition, (video/image)encoding, and metadata generation and processing. The memory unit 130may store data/parameters/programs/code/commands needed to drive the XRdevice 100 a/generate XR object. The I/O unit 140 a may obtain controlinformation and data from the exterior and output the generated XRobject. The V/O unit 140 a may include a camera, a microphone, a userinput unit, a display unit, a speaker, and/or a haptic module. Thesensor unit 140 b may obtain an XR device state, surrounding environmentinformation, user information, etc. The sensor unit 140 b may include aproximity sensor, an illumination sensor, an acceleration sensor, amagnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IRsensor, a fingerprint recognition sensor, an ultrasonic sensor, a lightsensor, a microphone and/or a radar. The power supply unit 140 c maysupply power to the XR device 100 a and include a wired/wirelesscharging circuit, a battery, etc.

For example, the memory unit 130 of the XR device 100 a may includeinformation (e.g., data) needed to generate the XR object (e.g., anAR/VR/MR object). The I/O unit 140 a may receive a command formanipulating the XR device 100 a from a user and the control unit 120may drive the XR device 100 a according to a driving command of a user.For example, when a user desires to watch a film or news through the XRdevice 100 a, the control unit 120 transmits content request informationto another device (e.g., a hand-held device 100 b) or a media serverthrough the communication unit 130. The communication unit 130 maydownload/stream content such as films or news from another device (e.g.,the hand-held device 100 b) or the media server to the memory unit 130.The control unit 120 may control and/or perform procedures such asvideo/image acquisition, (video/image) encoding, and metadatageneration/processing with respect to the content and generate/outputthe XR object based on information about a surrounding space or a realobject obtained through the I/O unit 140 a/sensor unit 140 b.

The XR device 100 a may be wirelessly connected to the hand-held device100 b through the communication unit 110 and the operation of the XRdevice 100 a may be controlled by the hand-held device 100 b. Forexample, the hand-held device 100 b may operate as a controller of theXR device 100 a. To this end, the XR device 100 a may obtain informationabout a 3D position of the hand-held device 100 b and generate andoutput an XR object corresponding to the hand-held device 100 b.

Examples of a Robot Applicable to the Present Disclosure

FIG. 20 illustrates a robot applied to the present disclosure. The robotmay be categorized into an industrial robot, a medical robot, ahousehold robot, a military robot, etc., according to a used purpose orfield.

Referring to FIG. 20 , a robot 100 may include a communication unit 110,a control unit 120, a memory unit 130, an I/O unit 140 a, a sensor unit140 b, and a driving unit 140 c. Herein, the blocks 110 to 130/140 a to140 c correspond to the blocks 110 to 130/140 of FIG. 16 , respectively.

The communication unit 110 may transmit and receive signals (e.g.,driving information and control signals) to and from external devicessuch as other wireless devices, other robots, or control servers. Thecontrol unit 120 may perform various operations by controllingconstituent elements of the robot 100. The memory unit 130 may storedata/parameters/programs/code/commands for supporting various functionsof the robot 100. The I/O unit 140 a may obtain information from theexterior of the robot 100 and output information to the exterior of therobot 100. The V/O unit 140 a may include a camera, a microphone, a userinput unit, a display unit, a speaker, and/or a haptic module. Thesensor unit 140 b may obtain internal information of the robot 100,surrounding environment information, user information, etc. The sensorunit 140 b may include a proximity sensor, an illumination sensor, anacceleration sensor, a magnetic sensor, a gyro sensor, an inertialsensor, an IR sensor, a fingerprint recognition sensor, an ultrasonicsensor, a light sensor, a microphone, a radar, etc. The driving unit 140c may perform various physical operations such as movement of robotjoints. In addition, the driving unit 140 c may cause the robot 100 totravel on the road or to fly. The driving unit 140 c may include anactuator, a motor, a wheel, a brake, a propeller, etc.

Example of AI Device to which the Present Disclosure is Applied

FIG. 21 illustrates an AI device applied to the present disclosure. TheAI device may be implemented by a fixed device or a mobile device, suchas a TV, a projector, a smartphone, a PC, a notebook, a digitalbroadcast terminal, a tablet PC, a wearable device, a Set Top Box (STB),a radio, a washing machine, a refrigerator, a digital signage, a robot,a vehicle, etc.

Referring to FIG. 21 , an AI device 100 may include a communication unit110, a control unit 120, a memory unit 130, an I/O unit 140 a/140 b, alearning processor unit 140 c, and a sensor unit 140 d. The blocks 110to 130/140 a to 140 d correspond to blocks 110 to 130/140 of FIG. 16 ,respectively.

The communication unit 110 may transmit and receive wired/radio signals(e.g., sensor information, user input, learning models, or controlsignals) to and from external devices such as other AI devices (e.g.,100 x, 200, or 400 of FIG. 15 ) or an AI server (e.g., 400 of FIG. 15 )using wired/wireless communication technology. To this end, thecommunication unit 110 may transmit information within the memory unit130 to an external device and transmit a signal received from theexternal device to the memory unit 130.

The control unit 120 may determine at least one feasible operation ofthe AI device 100, based on information which is determined or generatedusing a data analysis algorithm or a machine learning algorithm. Thecontrol unit 120 may perform an operation determined by controllingconstituent elements of the AI device 100. For example, the control unit120 may request, search, receive, or use data of the learning processorunit 140 c or the memory unit 130 and control the constituent elementsof the AI device 100 to perform a predicted operation or an operationdetermined to be preferred among at least one feasible operation. Thecontrol unit 120 may collect history information including the operationcontents of the AI device 100 and operation feedback by a user and storethe collected information in the memory unit 130 or the learningprocessor unit 140 c or transmit the collected information to anexternal device such as an AI server (400 of FIG. 15 ). The collectedhistory information may be used to update a learning model.

The memory unit 130 may store data for supporting various functions ofthe AI device 100. For example, the memory unit 130 may store dataobtained from the input unit 140 a, data obtained from the communicationunit 110, output data of the learning processor unit 140 c, and dataobtained from the sensor unit 140. The memory unit 130 may store controlinformation and/or software code needed to operate/drive the controlunit 120.

The input unit 140 a may acquire various types of data from the exteriorof the AI device 100. For example, the input unit 140 a may acquirelearning data for model learning, and input data to which the learningmodel is to be applied. The input unit 140 a may include a camera, amicrophone, and/or a user input unit. The output unit 140 b may generateoutput related to a visual, auditory, or tactile sense. The output unit140 b may include a display unit, a speaker, and/or a haptic module. Thesensing unit 140 may obtain at least one of internal information of theAI device 100, surrounding environment information of the AI device 100,and user information, using various sensors. The sensor unit 140 mayinclude a proximity sensor, an illumination sensor, an accelerationsensor, a magnetic sensor, a gyro sensor, an inertial sensor, an RGBsensor, an IR sensor, a fingerprint recognition sensor, an ultrasonicsensor, a light sensor, a microphone, and/or a radar.

The learning processor unit 140 c may learn a model consisting ofartificial neural networks, using learning data. The learning processorunit 140 c may perform AI processing together with the learningprocessor unit of the AI server (400 of FIG. 15 ). The learningprocessor unit 140 c may process information received from an externaldevice through the communication unit 110 and/or information stored inthe memory unit 130. In addition, an output value of the learningprocessor unit 140 c may be transmitted to the external device throughthe communication unit 110 and may be stored in the memory unit 130.

INDUSTRIAL APPLICABILITY

The above-described embodiments of the present disclosure are applicableto various mobile communication systems.

1. A method of selecting a sidelink relay in a wireless communicationsystem, the method comprising: selecting at least one candidate relay UEby a remote UE; and selecting a relay UE from the at least one candidaterelay UE by the remote UE, wherein the selection of the at least onecandidate relay UE is based on a sidelink signal strength of each of theat least one candidate relay UE and wherein the selection of the relayUE is based on comparison between a cell ID of each of the at least onecandidate relay UE and a cell ID selected according to a Uu link signalstrength.
 2. The method of claim 1, wherein the relay UE has the samecell ID as the cell ID selected according to the Uu link signalstrength.
 3. The method of claim 2, wherein based on a plurality ofcandidate relay UEs having the same cell ID as the cell ID selectedaccording to the Uu link signal strength, the remote UE considers thesidelink signal strength more preferentially.
 4. The method of claim 1,wherein the cell ID is included in a discovery message.
 5. The method ofclaim 1, wherein the cell ID selected according to the Uu link signalstrength is an ID of a cell of which signal strength among Uu linksignals measured by the relay is equal to or greater than a firstthreshold.
 6. The method of claim 1, wherein the cell ID selectedaccording to the Uu link signal strength is an ID of a cell of which Uulink signal strength measured by the relay belongs to a first range. 7.The method of claim 1, wherein the at least one candidate relay UE hasthe sidelink signal strength equal to or greater than a secondthreshold.
 8. The method of claim 1, wherein the at least one candidaterelay UE has the sidelink signal strength belonging to a second range.9. The method of claim 5, wherein the first range comprises one of apreconfigured value, a value transferred as a Medium Access Control(MAC) Control Element (CE), a value transferred by higher layersignaling, a value transferred by physical layer signaling, a valueselected by the remote UE, or a value included in a discovery message.10. A User Equipment (UE) in a wireless communication system, the UEcomprising: at least one processor; and at least one computer memoryoperably connected to the at least one processor and storinginstructions for enabling the at least one processor to performoperations when executed, the operations comprising: selecting at leastone candidate relay UE by a remote UE; and selecting a relay UE from theat least one candidate relay UE by the remote UE, wherein the selectionof the at least one candidate relay UE is based on a sidelink signalstrength of each of the at least one candidate relay UE and wherein theselection of the relay UE is based on comparison between a cell ID ofeach of the at least one candidate relay UE and a cell ID selectedaccording to a Uu link signal strength.
 11. The UE of claim 10, whereinthe UE communicates with at least one of another UE, a UE related to anautonomous vehicle, a base station, or a network.
 12. (canceled) 13.(canceled)